Preheat the oven to 180°C/350°F/Gas mark 4. Lightly grease a large casserole dish.Remove the skin and tubes from the liver. Season the flour with salt and pepper. Dredge each slice of liver in the seasoned flour.
Arrange layers of liver, onion and potatoes in the casserole dish, ending with a neat layer of potatoes. Heat the stock and pour in just enough to cover the potatoes. Cover the casserole dish and bake for about 1 hour until the liver is tender. Remove the lid and arrange the bacon rashers on top. Continue cooking, uncovered, until the bacon is crisp. Serve hot.